Abstract

Background Reaction time (RT) is a valuable component of the sport concussion assessment battery. RT is typically measured using computers
running specialised software, which limits its applicability in some athletic settings and populations. To address this, we
developed a simple clinical test of RT (RTclin) that involves grasping a falling measuring stick.

Purpose To determine the effect of concussion on RTclin and its sensitivity and specificity for concussion.

Materials and methods Concussed athletes (n=28) and non-concussed control team-mates (n=28) completed RTclin assessments at baseline and within 48 h of injury. Repeated measures analysis of variance compared mean baseline and follow-up
RTclin values between groups. Sensitivity and specificity were calculated over a range of reliable change confidence levels.

Results RTclin differed significantly between groups (p<0.001): there was significant prolongation from baseline to postinjury in the concussed
group (p=0.003), with a trend towards improvement in the control group (p=0.058). Sensitivity and specificity were maximised
when a critical change value of 0 ms was applied (ie, any increase in RTclin from baseline was interpreted as abnormal), which corresponded to a sensitivity of 75%, specificity of 68% and a 65% reliable
change confidence level.

Conclusions RTclin appears sensitive to the effects of concussion and distinguished concussed and non-concussed athletes with similar sensitivity
and specificity to other commonly used concussion assessment tools. Given its simplicity, low cost and minimal time requirement,
RTclin should be considered a viable component of the sports medicine provider's multifaceted concussion assessment battery.